In view of the admitted close correspondence between matter and mind, we may expect to find that the conception of sexually intermediate forms, if applied to mental facts, will yield a rich crop of results. The existence of a female mental type and a male mental type can readily be imagined (and the quest of these types has been made by many investigators), but such perfect types never occur as actual individuals, simply because in the mind, as in the body, all sorts of sexually intermediate conditions exist. My conception will also be of great service in helping us to discriminate between the different mental qualities, and to throw some light into what has always been a dark corner for psychologists--the differences between different individuals. A great step will be made if we are able to supply graded categories for the mental diathesis of individuals; if it shall cease to be scientific to say that the character of an individual is merely male or female; but if we can make a measured judgment and say that such and such an one is so many parts male and so many parts female. Which element in any particular individual has done, said, or thought this or the other? By making the answer to such a question possible, we shall have done much towards the definite description of the individual, and the new method will determine the direction of future investigation. The knowledge of the past, which set out from conceptions which were really confused averages, has been equally far from reaching the broadest truths as from searching out the most intimate detailed knowledge. This failure of past methods gives us hope that the principle of sexually intermediate forms may serve as the foundation of a scientific study of character and justifies the attempt to make of it an illuminating principle for the psychology of individual differences. Its application to the science of character, which, so far, has been in the hands of merely literary authors, and is from the scientific point of view an untouched field, is to be greeted more warmly as it is capable of being used quantitatively, so that we venture to estimate the percentage of maleness and femaleness which an individual possesses even in the mental qualities. The answer to this question is not given even if we know the exact anatomical position of an organism on the scale stretching from male to female, although as a matter of fact congruity between bodily and mental sexuality is more common than incongruity. But we must remember what was stated in chap. ii. as to the uneven distribution of sexuality over the body.